Electric valve translating circuits



Now 2, 1937. a F. W.-ALEXANDERSON 2,098,023

smacmrc wmvn wmsnume cIncuI'rs Filed Feb. 29, 1936 '2 sheets-sheep 1 Fig. I.

, Inventor: Emst F! WAlexanderson,

ov. 2, 1937. E. E. w. ALEXANDERSON fl fl ELECTRIC VALVE TRANSLATING CIRCUITS I Filed Feb. 29, 1936 2 Shets-Sheet 2 Inventoi": Ernst F. W Alexandersqn,

by misi Patented Nov. 2, 1937 PATENT OFFICE morale VALVE TRANSLATING cmourrs Ernst I. W. Alexander-son, .Schenectady, N. Yr,

assignor to General Electric Company, a corporation of New York Application February 29,

1936, Serial No. 66,433

9 Claims. (class-2'1) My invention relates to electric valve translating circuits and more particularly to control circults for electric valve translating apparatus.

Heretofore there have been devised many ar- 5 rangements for controlling the energization of electric valve apparatus in accordance with a combination of electrical conditions. For example, in electric valve frequency changing systerns the auxiliary control apparatus has been cumbersome and complicated. In many electricvalve translating systems employing electric valves to obtain a frequency transformation, the conductivity of the valves has been controlled by. mechanical means such as commutators or distributors acting in conjunction with electrical controlmeans. While these systems have proved satisfactory in many applications, there has been evidenced a decided need for control apparatus entirely electrical in nature for controlling the conductivity of electric valve means in accordance with a number or combination of electrical conditions.

It is an object of my invention to provide a new and improved electric valve translating circuit. It is another object of my invention to provide new and improved electric valve control circuits for controlling electric valve translating circuits. It is a still further object of my invention to provide a new and improved system for controlling the conductivity of electronic discharge devices of the type employing control members 'of the immersion-ignitor type. V

In accordance with the illustrated embodiments of my invention, I provide electric valve converting systems controlled by excitation circuits entirely electrical in nature'and in operation for controlling the conductivity of associated electric valve means in accordance with a number of diflerent predetermined electrical conditions. In accordance with one feature ofmy invention, I employ a control electronic discharge device having at least two control members or electrodes for controlling the conductivity of the main power electric valve means in accordance with a combination of electrical conditions. The control members of the electronic discharge devices are energized in accordance with at least two separate electrical conditions of an associated circuit, or circuits, to control the conductivity of the control discharge device and hence toefl'ect control of the conductivity ofthe main electric valve means. The control electronic discharge device is so constructed and arranged that the 55 control members act conjointly to eifect control of the conductivity of the discharge device. That is, the discharge device remains non-conductive until voltages of predetermined minimum values are impressed upon the respectivecontrol memhere. The control discharge device may be maintained non-conductive by impressing a suitable negative potential upon either of the control members.

In' accordance with another embodiment of my invention, instead of, employing a plurality of control members in a single valve, I provide an excitation circuit comprising two serially-connected electronic discharge devices each having a single control member for eflecting control of the conductivity of an electric valve of the gaseous type having an immersion-ignitor control member. The excitation circuit comprising the serially-connected electronic devices is energized in response to the voltage appearing across the anode and the cathode of the main electric valve, Each of the serially-connected electronic dis-' charge devices is energized in response to predetermined diiferent electrical conditions of the same or different circuits. When the predetermined electrical conditions are satisfied both electronic discharge devices are rendered conductive to effect energization of the control circuit for the main electric valve. So long as these electrical conditionsare met, the excitation circuit will impress periodically suitable potentials upon the control member of the main electric valve and conversely when either, or both, of the predetermined electrical, conditions depart from a predetermined range, or change in character, one or both of the control devices will be rendered non-conductive to interrupt the control circuit for the main electric valve.

For a better understanding of my invention,

reference may be had to the following description taken in connection with the accompanying drawings and its scope willbe pointed out in the appended claims.

Fig. 1 of the drawings, diagrammatically represents an embodiment of my invention as applied to an electric valve translating circuit em- .ploying two main power electric valves. An exthrough any conventional phase shifting device,

tion circuit comprising two serially connected electronic devices for each oi the main power electric valves is energized in response to the voltage appearing across the anode and the cathode of the associated main electric valve, and Fig. 3 shows a further embodiment of my invention as applied to an electric valve translating circuit for transmitting energy between an alternating current circuit of constant frequency and an alternating current of variable frequency such as a dynamo-electric machine of the synchronous type.

Referring now to Fig. l of the accompanying drawings, my invention is diagrammatically illustrated as applied to electric valve converting apparatus for transmitting energy between a three phase alternating current circuit and a single phase alternating current circuit. For the purpose of explaining and illustrating my invention, I have shown electric valves i and 2- of the gaseous type having anodes 3 and d, mercury pool cathodes 5 and 9 and immersionignitor control members 7 and 9 for interconnecting a polyphase alternating current supply circuit 9 and a single phase alternating current load circuit l through a transformer having a primary winding l2 and a secondary winding I3. 'The main power electric valves 8 and 2 are oppositely disposed or connected. That is,

the cathode of electric valve i is connected to the anode 4 of electric valve 3 through a conductor It, and the anode 9 of electric valve i and the cathode of electric valve 2 are connected to the same conductor of the polyphase sup,

ply circuit 3 through conductors i5 and it, re-

spectively, The cathode 5 of electric valve i and the anode 4 of electric valve 2 are connected to one side of the secondary winding l3 of transformer through a conductor l7, while the other terminal 0! the secondary winding i3 is connected to the supply circuit 9 through a conductor "8.

To provide means for controlling the conductivity of electric valves l and 2 in accordance with electrical conditions of the supply circuit 9 and the load circuit I9, I employ excitation circuits i9 and 29, respectively. The excitation circuits l9 and 20 are energized from the supply circuit 9 by a transformer 2| having primary windings 22 and secondary windings 23 and 24 such as the rotary phase shifting arrangement 25. Each of the excitation circuits l9 and 29 is energized from a suitable secondary winding of the transformer 2|. For example, the excitation circuit IQ for electric valve I comprisesthe secondary winding 23'01 transformer 2| for controlling the conductivity of the main electric valve in response to an electrical condition of the supply circuit 9. .A transformer 26, which may be of the type to supp a voltage of peaked wave form, having a primary winding 21 and a secondary winding 28, is employed to control the conductivity of electric valve I through an electronic discharge device 29, preferably of the gaseous type, in response to an electrical condition of the load circuit Ill. By the term "electronic discharge device of the gaseous type" I intend to include electric valves employing any ionizable medium such as a gas or vapor. The electronic discharge device 29 is provided with an anode 39, a cathode 3| and control members 22 and 33 and is employed to'correlate the predetermined electrical conditions of the s pp of the device 29 and when suitable voltages above predetermined minimum voltages are impressed upon the respective control members, the device 29 is rendered conductive. However, either or both-of the control members 32 and 33. may maintain the electronic discharge device 29 non-conductive if a voltage below a predetermined minimum value is impressed upon either of the control members.

To obtain a voltage of suitable magnitude and wave form for controlling the conductivity of the main electric valves I and 2, I employ circuits 34 in the excitation circuits l9 and 29, respectively, for impressing upon the immersionignitor control members I and 8 voltages in accordance with the desired sequence of operation. The circuits 99 each comprise a capacitance 35 which is periodically charged from the secondary winding 23 through a resistance 36 neutral 38 of secondary winding 23. To im press upon the control member 32 of electronic discharge device 29 a potential of suitable magnitude and phase relation relative to the voltage of the supply circuit 9, I use a phase shifting circuit connected between the lower terminal of the secondary winding 23 and the neutral connection 38 comprising a capacitance t9 and resistance 66. A resistance 4| is connected. in series with this phase shifting circuit and the control member 32 of electronic discharge device 29. The common connection between capacitance 35 and resistance 46 is connected to the cathode 3| of electronic discharge device 29 by a conductor 42. One terminal of the excitation circuit l9 for the electric valve 5 is connected to the immersion-ignitor control memher I of electric valve I through a conductor (it,

I ondary winding 28 of transformer 26 is connected to the cathode 3| of electronic discharge device 29 and the left-hand terminal 01' secondary winding28 is connected to the control member 33 through a current limiting resistor 45.

In explainingthe operation of the embodiment of my invention diagrammatically shown in 'Fig.

1, let it be assumed that the alternating current supplycircuit 9 is of a higher frequency than the alternating current load circuit l0 andthat current is being transferred-between these two circuits by the interconnected electric valve means i and 2. Under the assumed conditions. i

the electric valve I should be rendered conductive, for example; during positive halt cycles of the alternating potential of the supply circuit 9 and concurrently during an interval corresponding to a positive half cycle of the potential 01' the the higher frequency potential of the supply cirload circuit Id. In other words, the electric valves and 2 will be conductive alternately during alcuit 9 to supply current to the secondary winding I3 of transformer 'Il. Each of the electric valves] and 2 will be rendered conductive'intermittently to efiect transfer of current from the supply circuit 9 to the load circuit I9 during half cycles of predetermined sign of the lowerfrequency potential of alternating current circuit iii. For example, the excitation circuit i9 will operate to impress voltage of suitable wave form upon the control member I of electric valve I in predetermined phase relation with the voltage of the alternating currentcircuit 9. The capacitance 35 of the circuit 34 will be charged during positive half cycles of alternating potential of circuit 9 by means of the secondary winding 23 of transformer 2|. 29 is rendered conductive in response to suitable potentials being impressed upon the control members 32 and 33, the capacitance 35 will discharge through the circuit comprising conductor 43, control member I of electric valve I, conductor 44, electronic device 29, conductor 42, and the capacitance 95. The electronic discharge device 29 will be rendered conductive only during those intervals in which predetermined electrical conditions of the alternating current circuit 9 and the alternating current circuit iii are satisfied. In this manner, the capacitance 35- will he charged during positive half cycles of the relatively higher frequency of the alternating current circuit 9 and will bedischarged during the following half cycles of potential. The polarities of the potentials impressed on the control members 32 and 33 of electronic discharge device 29 by the phase shifting circuit comprising capacitance 39 and resistance 49 and the secondary winding 28 of transformer 25, respectively, determine the instant at which the device 29 is rendered conductive. Since the control members 32 and 33 of device 29 must act conjointly to render the device 29 conductive, the electric valve I will be rendered conductive at only those intervals during which it is. desired to.v transmit power from the alternating current circuit 9 to I relative to the potential impressed on the anode 3 of electric valve l. While for the purpose of explaining my invention I have shown two elec-- tric valves interconnecting alternating current circuits, it should be understoodthat my invention in its broader aspects may'be applied to electric valve translating circuits generally employing either a single electricvalve or a pluilar to the embodiment of my invention shown 9 in Fig. l and corresponding elements have been assigned like reference numerals. 1 Any suitable electric valve aggregate, such as electric valves I and 2 of the gaseous type employing an immersion-ignitor control member, is employed for transmitting energy between alternating current supply circuit 9 and alternating current load circult Ill. To control the conductivity of the electric valves l and 2 during predetermined intervals, I employ excitation circuits 49 and 41, respective- When the electronic discharge device 7 1y. Each of the excitation circuits 49 and 41 is energized in accordance with the voltage appearingacross the anode and cathode of the respective main power electric valves I and 2 and in accordance with predetermined electrical conditions of the supply circuit 9 and the load circuit III and each comprises two serially-connected electronic devices 48 and 49, preferably of the gaseous or vapor type, having anodes 59 and SI, cathodes 52 and 53 and control members 54 and 55, respectively.

The conductivity of the electronic device 48 is controlled in accordance with an electrical condition, such as the voltage, of the load circuit In through a transformer 55 having a primary winding 51 and a secondary winding 58, and the conductivity of the electronic device 49 is controlled in accordancewith an electrical condition, such as the voltage, of supply circuit 9 through a transformer 59 having a primary winding Gil and a secondary winding ii. The transformer 59 is energized from the supply circuit 9 through the rotary phase shifter 25, secondary winding 23 of transformer 2|, conductors 62 and 63 and unidirectional conducting device 64. A transformer 55 having secondary windings 65 and 51 is energized from any suitable auxiliary source of alternating potential to energize the cathodes 52 and 53 of electronic devices 48 and 49, through conductors 58 and 69, respectively. A potential which varies in accordance with an electrical condition of the load circuit I0 is impressed across the control member 54 and cathode 52 of electronic device 48 by secondary winding 58 of transformer 55, through a conductor 10, a suit- .able negative voltage biasing means such as a battery II, and a current limiting resistance 12, conductors 88 and a conductor 13. A potential, which varies in accordance with an electrical condition of the supply circuit 9, is impressed across the control member 55 and cathode 53 of electronic device 49 by the secondary winding SI of transformer 59, through a conductor 14 which is connected to the right-hand terminal of winding 6l, a current limiting resistance 15, and a conductor 16 which connects the cathode 53 to the left-hand terminal of. the secondary winding SI of transformer 59. The left-hand terminal of the secondary winding 6| of transformer 59 is also connected to the control member I of electric valve I by a conductor 11. The anode 59 of electronic device 43 is'connected to the anode 3 of electric valve I through a resistance 18 and any conventional current limiting device, such as a fuse l3.

As explained in connection with the operation of the embodiment of my invention diagramf matically shown in Fig. ,1, the embodiment of myinvent'ion represented in Fig. 2 may be best explained by considering the operation of the system when-the frequency ofthe supply circuit 9 is greater thanthe frequency of the load circuit Ill. To obtain the desired periodic energization of the'electric valves I and 2, and hence to control the conductivity of the valves I and 2 at predepotentials of circuits 9 and III. the electronic discharge devices 48 and 49 in each of the excitation circuits and 41 act conjointly to effeet energization at these predetermined intervals. Since the conductivity of'the electronic device 49 is controlled in accordance with an 7 electrical condition of the supply circuit 9 and since the conductivity of the electronic device 48 is controlled in accordance with an electricalcon- Gil termined times relative to the polarities of the in which these predetermined conditions are satisfied, electronic devices 48 and 48 will be ren dered'conductive to effect energizationpf the immersion-ignitor 1 through a circuit comprising fuse 18, current limiting resistor 18, electronic device 48, electronic device 48, conductor 18 and conductor 11.

It should be understood that while I have described in detail the operation of the excitation circuit 48, the excitation circuit 81 operates in a similar manner to control the conductivity of electric valve 2 during alternate half cycles of the high frequency potential of the alternating current supply circuit 8. Furthermore, it should be understood that I may employ a group of valves similarly disposed in regard to the other phases of the alternating current supply circuit 8 to effect energy transfer between polyphase alternating current circuits.

Referring now to Fig. 3 of the accompanying drawings, a further embodiment of my invention is diagrammatically illustrated as applied to an electric valve translating system for transmitting energy between an alternating current circuit 88 and a dynamo-electric machine 8| of the synchronous type by means of any suitable electric valve aggregate such as the electric valves 82 to 81, inclusive, of the gaseous type having immersion-ignitor control members 88. The dynamoelectric machine 8| is provided with a plurality ofinductive phase windings 88, 88, and 8|, an electrical neutral 82, a rotating member 83 and an inductive field winding 84. The electric valves 82-81, inclusive, are energized from the alter-' nating current supply circuit 88 through atransformer 85 having a secondary winding 88 and an electrical neutral 81. Electric valves 82 and 85, 83 and 86, and 84 and 81 serve to energize phase windings 88, 88 and 8|, respectively, of machine 8| in a predetermined sequence to establish a rotary field in the machine and to effect thereby rotation of the member 83. The unidirectional current which these groups of valves supp y to the respective phase windings is returned from the electrical neutral 82 through the field winding 84 to the electrical neutral 81 of transformer 85 through a conductor 88. To control the conductivity of each of the electric valves 82-81 in accordance with an electrical condition of the supply circuit 88 and the machine 83, such as the voltage of the supply circuit 88 and the voltage of the phase windings 88-8I, I employ a plurality of excitation circuits 88488 inclusive, each of which isassociated with a predetermined different one of the electric valves 82-81. For example, the excitation circuit I84 is associated with the electric valve 81. The excitation circuits 88- I84, inclusive, are provided with electronic discharge devices I85- I I8, respectively, preferably of the gaseous type, each having an anode HI, a cathode H2 and control members H3 and 4. Each of these excitation circuits is also arranged similar to the excitation circuits I8 and from the supply circuit 88 through any suitable phase shifting arrangement such as the rotary phase shifter H5.

To provide means for controlling, the conductivity of the electric valves 82 to 81 in accordance with an operating condition, such as the speed of the dynamo-electric machine 8|, a distributor mechanism 8 is employed. This distributor may be of the electrical or mechanical type and as shown is of the mechanical type comprising a rotary conducting segment Ill which establishes contact successively with brushes H8, H8, and I28 to eifect energization of the proper excitation circuit at a predetermined time relati ve to the speed and position of the rotating member 83. For example, the brush I I8 connects excitation circuits IM and I84 to the output of the phase shifter II through conductors |2| and I22 and unidirectional conducting devices I23 and I24. Since the potentials impressed between the anodes of electric valves 84 and 81 are opposite in phase, that is 180 electrical degrees out of phase, it is desirable to effect energiz'ation of the associated excitation circuits |8| and I84 only during half cyclesof predetermined sign. Since the unidirectional conducting devices I28 and I24 are oppositely disposed, the excitation circuits I8I and I84 are energized during half cycles of opposite polarity of the alternating potential supplied by the phase shifter I I8. Similarly, brush II 8 is connected to excitation circuits 88 and I82 through a conductor I25 and conductor I 2|, and brush I28 connects excitation circuits I88 and I83 to the output of phase shifter 5 through a conductor I26 and conductor I2I.

In addition) to the above mentioned means forcontrolling'the conductivity of the electric valves 82-81 in accordance with an operating condition of the dynamo-electric machine 3|, I employ a transformer |21 having primary windings I28 energized in accordance with the voltage of phase windings 88-9I, and secondary windings I28-I34, inclusive. Secondary windings I28 and I38 of transformer I21 are connected to control members 3 of the electronic devices I81 and H8, respectively, through conductors I35 and I88 to control the energization of control members H3 and hence to control the conductivity of these valves in accordance with an electrical condition of the associated phase winding 8| of machine 8|. Similarly, secondary windings I3I, I32 and I33, I34 are associated with electronic devices I86, I88 and I85, I88, respectively, through conductors I31-I48, respectively.

A switch I4I,having stationary contacts I42 and I43 and a movable contact I44 may be employed to render. the distributor II8 ineffective by short circuiting the brushes ||8-I28.

The operation of the embodiment of my invention diagrammatically shown in Fig. 3 may be best explained by considering the operation of the electric translating apparatus when the supply circuit 88 is energized from a source of suitable frequency, such as an ordinary commercial frequency, and the dynamo-electric machine I is not rotating. Let it be further assumed that contact I44 of switch I4| engages contact I48 and that the phase of the alternating voltages impressed upon the immersion-ignitor control member 88 of electric valves 82-81is sufflciently retarded in phase relative to the voltage impressed upon the associated anodes so that the average voltage,-and hence the average current, which these valves supply is relatively small 'and insufiicient to cause rotation of the member 88. Under the assumed conditions, the distributor H6 is in a position so that the conducting segment 1 is in contact with brush 8 to effect 6 energization of excitation circuits m and llll.

be advanced by means of phase shifter 5, the

average voltage, and hence the average current, furnished by electric valves 84 and 81 will be increased and since the rotating member 88 of machine 8| is in a torque producing position relative to the phase winding 8|, the member 88 .will be caused to accelerate at a rate dependent upon the connected load. Assuming that the interactions of the magnetomotive forces of the phase winding ii and field winding 98 of machine 8| are in the proper directions so that the member. 98 rotates in a clockwise direction, the conduct.- 118 se ment 1 of distributor 6 will establish contact with brush 8 to effect energizatlon of excitation circuit-s 89 and "I2, which in turn will render electric valves 82 and 85 conductive to ,supply unidirectional current to the phase winding 88.- In this manner, it will be understood that the distributor Iii eilects energization of the proper excitation circuits to render electric valves 82-81 conductive in predetermined sequence to establish the desired-periodic energiz'ation of the phase windingsdHl when the rotating member 98 is in a torque producing position relative to the respective phase windings. It should also be noted that the distributor H6 ,eflects transfer or commutation of unidirectional the electric valves 82-81 by means entirely electrical in nature and operation, the movable memher I of switch Ill may be placed in contact with stationary members I82 to render the distrlbutor iii ineflective. Since the transformer 121 is energized in accordance with the voltage of the phase windings 88-81, the conductivity of the electronic devices III to III will be controlled in accordance with an operating condition 01' the once with the voltage of the supply circuit88'. The electronic devices Ill-l 18, through the con- 'trolmembcrs H8 and I I4, supply current to the immersion-ignites control members ll, of electric as valves our only during thoseintervals in'which Althomhin ligJ oftheaccompanylngdraw- -ingsIhaveshownnwinventionasappliedtoan electric valve translating circuit ior transmitting 70 energy between]. single phase alternating current circuit and a variable frequency load circuit, it should be understood that my invention in its broaden aspects may be l-lmlled to electric valve translating circuits generally for transmitting- 75 energy between alternating and direct eta-rent,

machine 8l-andwlllalso be controlled in accord-- circuits or between alternating current circuits of'variabl frequency. I

My co ding patent application Serial No.

66,432, filed February 29, 1936, describes an electric valve translating system employing an electronic discharge means of the gaseous type having two control members for conjointly controlling the conductivity of the electric valve system in accordance with two independent electrical conditions; that application is assigned to the assignee of the present application. The frequency changing systems of the above discussed drawings are disclosed .and claimed in my copending application Serial No. 112,041, filed No-' vember 21, 1936, and the electric valve motor controlling system, of which the arrangement of Fig. 3 is illustrative, is disclosed and broadly claimed in my copending application Serial No. 112,042, filed November 21, 1936, both applications being divisions of this application and both being assigned to the assignee of the present application. 1

While I have shown and described my invention as applied to a particular system of connections-and as embodying various devices diagrammatically shown, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and

- the true spirit and scope of my invention.

What I claim as 'new and desire .to secure by Letters Patent of the United States, is:

1. In combination, a supply circuit, a. load circuit, electric valve meansiinterconnecting said circuits, and a circuit comprising electronic discharge means of the gaseous type for controlling the conductivity of said electric valve means conlointly in accordance witli; predetermined electrical conditions of said supply circuit and said load circuit, said electronic discharge means comprising two controlmembers each energized in accordance with a different one of said electrical I N conditions. 2. In combination, a supply circuit, a load circuit, electric valve means of the gaseous type interconnecting said circuits, and a circuit comprising electronic discharge means having a pair of control members for controlling the 'conductivity thereof to effect control of the conductivity of said electric valve means coniointly in accordance with predetermined electrical conditions of said supply circuit and said load circuit, and means for energizing one of said control members in accordance with an electrical condition of said supply circuit and for energizing the other of said control members in accordance with an electrical condition ofsaid load circuit.

3. In combination, a supply circuit, a load circuit, electric valve means interconnecting said circuits, and anexcitation circuit for controlling the conductivity of said electric valve means comprising electronic discharge means of the gaseous typehaving a pair of control members for conjointly controlling the conductivity thereof, means for impressing on one of said control members a potential which varies in accordance with an electrical condition of said supply circuit and means for impressing on the other of said control members a potential which varies in accordance with-an electrical condition of said load circuit to control the conductivity of'said electric valve means coniointly in accordance with said conditions. I

4. In combination, a supply circuit, a load circuit, electric valve means interconnecting said circuits, and an excitation circuit for controlling the conductivity of said electric valve means comprising electronic discharge means of the gaseous type, means for rendering said electronic discharge means conductive conjointly in accordance with predetermined electrical conditions of said supply circuit and said load circuit, and means associated with said excitation circuit for controlling the phase relationship between the potential of said supply circuit and the time at which said electric valve means is rendered conductive.

5. In combination, a supply circuit, a load circuit, electric valve means interconnecting said circuits, an excitation circuit for controlling the conductivity of said electric valve means comprising electronic discharge means of the gaseous type, control means associated with said supply circuit for controlling the conductivity of said electronic discharge means, control means associated with said load circuit and acting conjointly with said first-mentioned control means torender said electronic discharge means conductive in accordance with a predetermined concurrent relationship between predetermined electrical conditions of said supply circuit and said load circuit, and means associated'with said excitation circuit to control the phase relationship between the potential of said supply circuit and the time at which said electric valve means is rendered conductive.

6. In combination, a supply circuit, a load circuit, electric valve means interconnecting said circuits, and an excitation circuit for controlling the conductivity of said electric valve means comprising an electronic discharge device of the gaseous type including an anode, a cathode and at least two control members, means associated with said load circuit and connected to one of said control members tending to render s'aid electronic discharge device conductive in ac cordance with a predetermined electrical condition of said load circuit and means associated with said supply circuit and connected to the other of said control members and co-operating with said first-mentioned control member to render said electronic discharge device con-.

ductive in accordance with a predetermined electrical condition of said supply circuit.

'7. In combination, a supply circuit, a load circuit, electric valve means interconnecting said circuits, and an excitation circuit for rendering said electric valve means conductive only when predetermined electrical conditions of said supply circuitand said load circuit are satisfied comprising an electronic discharge device of the gaseous type including an anode, a cathode and at least two control members, means associated with said load circuit and connected to one of said control members tending to render said electronic discharge device conductive in accordance wth a predetermined electrical condition of said load circuit and means associated with said supply circuit and connected to the other of said control members and co-operating with said first-mentioned control member to render said electronic discharge device conductive when saidppredetermined electrical condition of said load circuit is satisfied and in accordance with a predetermined electrical condition of said supply circuit.

8. In combination, a supply circuit, a load circuit, electric valve means of thegaseous type comprising a control member of the immersion ignitor type interconnecting said circuits, and an excitation circuit for controlling the conductivity of said electric valve means comprising an electronic discharge device of the gaseous type including an anode, a cathode and two control members, means including a source of alternating current, a capacitance connected to be energized from -said source for energizing said immersion-ignitor control member through' said 4 electronic discharge device, means associated with said supply circuit and connected to one of said control members of said electronic dis-- charge device tending to render said electronic discharge device' conductive in accordance with a predetermined electrical condition of said supply circuit and means associated with said load circuit and connected to the other of said control members of said electronic discharge device for rendering said electronic discharge device conductive in accordance with the predetermined electrical condition of said load circuit to effect the discharge of said capacitance through said immersion-ignitor.

9. In combination, a supply circuit, a load circuit, electric valve means interconnecting said circuits, and an excitation circuit for controlling the conductivity of said electric valve means in 

